Before you begin selling information products on the Internet, you want to make sure you're targeting a niche that will be profitable for you in the short and long-term. A niche just means your target audience.
Some niches, as you'll discover, aren't as profitable as others. You need to look at your audience and see if they're willing (and able) to spend money for the solutions they're seeking.
For instance, golfers have deep pockets because the game of golf in itself is expensive. They're also rabid fans of the game who would do anything to improve their score or beat their competitors on the links.
But another niche, such as single moms on a budget may not be willing to pay $67 for an information product showing them how to get organized. Sometimes it depends on the solution itself. Targeting this same niche of single moms, you may find some are willing to pay $47 for an eBook that shows them how to make more money working from home than they do in their regular 9-5 jobs.
One good place to start is with online groups and forums. You can go to iVillage or Yahoo and see what kind of groups garner the most posts. Men's groups such as AskMen might give you insight into what kind of information products this portion of the population might need that help you generate a handsome profit.
You're not just looking for a broad group of people to cater to - you're looking for those with a lot of problems. When you start creating your information products, you'll want to build an empire of products that all focus on the same niche, allowing you to market to existing, loyal customers who buy from you time and time again.
Sometimes, you'll find one large niche and then realize you need to build your information product line around a more targeted, narrow niche of people. For instance, parents in general have many problems you could address, such as raising smart kids, dealing with discipline, and saving money.
But you can then narrow that niche to moms or dad and dig deeper by focusing on parents of multiples or parents raising kids with physical ailments. Just remember that an information product is not really a product at all - it's a solution, so it needs to be marketed as something that will improve lives.